Get him some breifs!!! Nobody should be expected to squat wide without briefs in my opinion.
Also, this is a tough sport. Not many can hack it. In fact, very few can hack it. You have to be born with some talent, despite what any motivational coaching type person tries to tell you. And more important than talent, you have to have heart.
Not to talk down about your cousin, but it sounds to me like he just is seriously lacking in the old guts department.
You have to be able to take an extreme amount of pain to do well in this sport. I am not talking about winning meets or setting records as doing well, I am talking about making gains. Pain begets gains.
If a person is not willing to do what it takes, nothing you can do is going to make them want to sacrifice and do what it takes. Now, regarding motivational techniques. Yelling is fine for me, calling me a puss, or challenging me, is great, but hitting me is a big no no.
However, if someone gets in someone else's face, and that person backs down, or acts scared, then, in my opinion, they are a lost cause. If I get in bigokie's face, or he gets in mine, we get mad, and by God, either lift the weight, or damn near pass out trying.
I have lifted in meets with the Springfield crew, and have trained with Genemachine and AnimalMass, and can tell you, they are intense, motivated people, who have both come a long ways, and I expect will continue to progress in the future. They are both good examples of hard work over genetics. For those of you who have not met them, they are tall. Now in general, tall is a good thing, but in Powerlifting, tall is usually not advantageous. Especially squatting and benching. However, both of these guys have made incredible strides in adding muscle and strength. I think Animalmass has put on like 80 or 90 lbs since he started lifting. Now that is some hard work paying off.
But they both have an attitude that says, whatever it takes to get it, I will do it. None of this, the belt pinches me, the shirt hurts, or whatever. Well, the belt pinches everyone, shirts are painful for us all, but real men, and women (nods to Spatts) are able, and are willing to trade this pain for the personal satisfaction, and glory that comes from lifting heavier and heavier weights.
I say, give him the opportunity and information to get stronger, and then leave him alone. If he is timid, this is no place for him. Let him make up his own mind, and if he want's to quit, it is for the best.
B.